Apparatus and method for use in the treatment of hammertoe

Abstract

The apparatus and method is directed to a pair of self-tapping, interconnecting, externally and internally threaded devices that, when installed between two separate pieces of material, will draw and hold the material together as a single threaded unit. While the pair of threaded devices are being fastened into the host material, due to the unique design of their threads, no radial outward forces are produced that could cause cracking or splitting of the sections of the material into which they are installed. The external threads are helically defined into the exterior of each half of the device with a right hand thread defined into one half and a left hand thread into the other half. When the two halves are being fastened together, the increased thread pitch on one of the halves continuously draws the halves into each other even when the internal threads have already been maximally tightened.

We claim: 
     
       1. An apparatus for coupling two pieces of host material together, comprising: a distal half and a proximal half, each said half having a longitudinal axis which, when conjoined, couple respectively a first piece of host material to a second piece of host material along a now common longitudinal axis, said distal half having a thread pattern helically disposed on an exterior surface, wound in one direction, said proximal half having a thread pattern helically disposed on an exterior surface wound in a second direction, opposite from said distal half, means to removeably attach said distal and proximal halves together such that when united together, further rotation of either said proximal or distal half causes said halves to move one relative to the other until they are either dissociated or bound together, wherein said threads on said exterior surfaces each have a portion defining self-tapping threads located adjacent bores which pass through said exterior surfaces into interiors thereof, said self-tapping threads having tooth flanks on each half facing each other and defining an included angle relative to said longitudinal axes of said proximal and distal halves of less than 90 degrees, and each thread of said self-tapping threads has an opposite flank on each tooth with an included angle relative to said longitudinal axes of said proximal and distal halves greater than or equal to 90 degrees, wherein said means to removeably attach said distal and proximal halves together includes a peg projecting axially from said distal half and having a thread disposed at a terminus for threaded axial registry with a complementary formed thread disposed in said proximal half, wherein said means to removeably attach said halves further includes wrench flats disposed on an exterior surface of said peg. 
     
     
       2. The apparatus of  claim 1  wherein said means to removeably attach said halves further includes a hexagonal bore formed in said halves. 
     
     
       3. The apparatus of  claim 1  wherein said thread pattern on said distal half has a pitch different than that of said thread pattern on said proximal half.